DEFINTIONS

Empennage
1. The tail assembly of an aircraft.
2. An arrangement of stabilizing surfaces at the tail of an aircraft.

Origin: from French, from empenner ‘to feather an arrow’, from em- ‘in’ + penne ‘a feather’ (from Latin penna ).

Fuselage
1. The fuselage is the main body of an airplane, missile, or rocket. It is usually cylindrical in shape.
2. The central body portion of an aircraft designed to accommodate the crew and the passengers or cargo.

Origin: From French, from fuselé "spindle-shaped" (from past participle of fuseler "to give the shape of a spindle to," going back to Middle French, derivative of fusel "spindle," diminutive of fus "spindle," going back to Latin fūsus.

Spindle
1. A rounded rod, usually of wood, tapering toward each end, used in hand-spinning to twist into thread the fibers drawn from the mass on the distaff, and on which the thread is wound as it is spun.
2. The rod on a spinning wheel by which the thread is twisted and on which it is wound.

Origin: Old English spinel; related to spinnan to spin, Old Saxon spinnila spindle, Old High German spinnala.

Monocoque
1. A type of construction (as of a fuselage) in which the outer skin carries all or a major part of the stresses.
2. A type of vehicle construction (as of an automobile) in which the body is integral with the chassis.
3. Designating or of a kind of construction, as of a rocket, in which the skin or outer shell bears all or most of the stresses.
Origin: From French, from mono- ‘single’ + coque ‘shell’.

Servo tab
A servo tab is a small, hinged device installed on an aircraft control surface to assist the movement of the control surfaces. They provide a mechanical advantage to the pilot.

Origin: From “servomechanism” - an automatic device used to correct the performance of a mechanism.

Reciprocating Engine

A reciprocating engine is a type of engine that uses one or more pistons to transform the thermal energy of the fuel into rotary motion. It is known as a reciprocating engine because of the piston’s reciprocating or backward and forward motion that generates the mechanical power required to complete the task. A reciprocating engine is also known as a piston engine because it uses a piston. 

Origin: From the word “reciprocate”, meaning to respond to (a gesture or action) by making a corresponding one. From Latin reciprocat- ‘moved backwards and forwards’, from the verb reciprocare, from reciprocus (based on re- ‘back’ + pro- ‘forward’).